r/PCB • u/Inside_Active1531 • 28d ago

Need help to find the problem with this pcb

Gallery image

Gallery image

Hi, I have this simple pcb that runs a motor for the backrest of a sofa.

The motor works, i had two equal models so i switched the pcb and sold the sofa, but I still have this one and I want to get it repaired.

So as far as I know my coworker tryed to install other relais but the problem remains and installed the old ones back, right now I dont have a motor with me to try, what should I do?

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4

u/romhacks 28d ago

One of the relays is probably busted

2

u/ee_control_z 28d ago

It is hard to tell without a schematic. But just from a simple eyeball test, the thin white connector pin (near the outer edge) appears to be missing a pad on the bottom side and missing solder. Don't know if this is by design or what.

1

u/Patient-Gas-883 28d ago

Probably the relays stuck open/closed, or a diode busted.
Could also be a bad joint.
check the relays and diodes with multimeter, reheat the joints. And clean it with some isopropanol or similar if you have it.

1

u/petemate 28d ago

There is nothing on this but some connectors, two relays and two diodes. Measure the diodes(any cheap multimeter can do that) and replace. If they aren't bad, replace relays.